Many smart wearable devices have been introduced in the past decade. They provide extensive information by means of visual display or sound, employ smart sensors, use sophisticated processing and communication devices, and they are well integrated with the user's other smart devices.
The smartwatch has become the most popular smart wearable device in recent years. It allows the user to download, read and communicate information, conduct standard phone operations, and monitor their body's activities and health using sophisticated sensors. The integration of the smartwatch with other popular portable devices (in particular, the smart phone) brings forth many more sophisticated applications and uses.
While smartwatches have widely adopted the touch screen technology that made the mobile phone a great success, the inherently tiny screen found on a typical smartwatch is frequently too small for selective touch commands. The finger that touches the screen is always in the way, obstructing the display. Touch screen gestures often cause unintended activation of links that may be present on the screen during scrolling, and result in fingerprints and dirt being left on the display. It may also be difficult to see which input to make on the small screen, particularly for those with diminished eyesight.
The tiny screen found on a smartwatch is simply way too small to perform any common multi-touch commands like pinching, rotation, and other gestures. Placing two fingers on the screen will block most of the display area. Meanwhile, multi-touch gestures remain crucial for the user interface in many common applications. For example, the user may want to browse a map or a picture on the small screen of the smartwatch, or change the image scale. Typing data on the small screen is also close to impossible on wearable devices.
In the prior art, various devices with limited screen capabilities are routinely interfaced with external tactile input devices like the common mouse or touchpads. However, connecting such conventional tactile input devices is not possible for wearable devices since the device is worn on moving and often space limited surfaces. User interface solutions like virtual keyboard projection systems were deployed in recent years for smartphones, tablets and other mobile devices. However, this solution is not suitable for wearable devices because the body surface on which the virtual keyboard will be projected is neither flat nor even, and the skin has a texture and color that may not display projection images clearly. In addition, most wearable devices are low profile (i.e. they have low height), which makes proper projection of virtual keyboards close to impossible.